A two-year and four-month, male German Shepherd was referred for exercise intolerance and panting. Irregular heart auscultation (250 beats per minute (bpm)) and pulse deficits were noted on physical exam. Electrocardiogram (ECG) showed irregular, narrow-QRS tachycardia without P waves compatible with coarse atrial fibrillation (AF). A 24-h ECG showed sustained AF (mean ventricular response rate 92 bpm). Echocardiography showed no structural abnormalities. Given the young age and presence of AF-related symptoms, rhythm control was preferred. Transthoracic electrical cardioversion was successfully performed six weeks later but AF recurred within 24-h. Sotalol was started but discontinued due to poor tolerance and AF persisted.

Seven months after AF diagnosis, radiofrequency catheter ablation (RFCA) aiming for pulmonary vein isolation was performed under general anaesthesia. After transseptal puncture, three-dimensional electroanatomical mapping of the left atrium was performed. Point-by-point pulmonary vein isolation was achieved by RFCA. Seventy-eight RFCA lesions were placed in the left atrium encircling the three pulmonary vein ostia followed by electrical cardioversion. No complications occurred and the dog was discharged with amiodarone.

In the immediate post-operative phase, there was recurrence of persistent AF requiring electrical cardioversion. Furthermore, at one month after the ablation, the dog experienced a single and transient paroxysm of AF. Since then, stable sinus rhythm (SR) was retained on daily ECG monitoring at home and confirmed by 24-h ECG three months post-operatively. Amiodarone was stopped subsequently. At the time of writing (one year post-operative), the dog remains in SR with normal exercise tolerance.

一只两岁零四个月的雄性德国牧羊犬因运动不耐受和气喘而被转诊。体检时发现心脏听诊不规则（每分钟 250 次 (bpm)）和脉搏缺陷。心电图 (ECG) 显示不规则、窄 QRS 心动过速，无 P 波，与粗心房颤动 (AF)相符。24 小时心电图显示持续性 AF（平均心室反应率为 92 bpm）。超声心动图未显示结构异常。考虑到年轻且存在 AF 相关症状，首选节律控制。六周后成功进行了经胸电复律，但房颤在 24 小时内复发。开始使用索他洛尔，但由于耐受性差而停药，房颤持续存在。

AF诊断7个月后，在全身麻醉下进行了旨在肺静脉隔离的射频导管消融术（RFCA）。房间隔穿刺后，对左心房进行三维电解剖测绘。通过RFCA实现逐点肺静脉隔离。78 个 RFCA 病灶位于左心房，环绕三个肺静脉口，随后进行电复律。没有出现并发症，狗在接受胺碘酮治疗后出院。

在术后不久，持续性房颤复发，需要电复律。此外，在消融后一个月，狗经历了一次短暂的房颤发作。此后，每天在家进行心电图监测，保持稳定的窦性心律（SR），并在术后三个月通过24小时心电图确认。随后停用胺碘酮。在撰写本文时（术后一年），狗仍处于 SR 状态，具有正常的运动耐量。